Human vision#
Fig. 2 shows a simplified cross section of the human eye.
Fig. 2 Simplified diagram of the human eye.#
The eye is basically composed of:
the cornea (french: cornée), a transparent tissue that covers the surface of the eye,
the lens (french: cristallin), a second transparent tissue that refracts light onto the retina by changing its shape,
the retina (french: rétine) which lines the inside of the posterior portion of the eye. The light from an object is imaged on the retina when the eye is properly focused.
In addition, the human eye’s retina contains two kinds of receptors. The rods (french: bâtonnets) provide an overall picture of the field of view and are sensitive to low levels of illumination. Besides, the cones (french: cônes) allow color vision. There are three types of cones which are sensitive to short (S), medium (M) and longer (M) wavelength of the visible light (see Fig. 3). Basically, they are sensitive to blue, green and red light. Rods and cones are connected to the brain by nerves, which proceeds to the image analysis.
Fig. 3 Responsivity of the three kinds of cones, compared to electromagnetic spectrum.#